This invention relates to flame retardant compositions containing at least one tetrahalophthalate ester and an ABS resin. Additionally this composition may also contain one or more brominated and/or chlorinated compounds in an amount to provide additional flame retardancy to the ABS resin. This invention also comprehends the method of improving the flame retardancy and processability of the ABS resins by using these tetrahalophthalate esters along or in combination with one or more bromine and/or chlorine compounds.
ABS resins are known in the art as a class of thermoplastics which are characterized by excellent properties such as chemical resistance, abuse resistance, stain resistance, etc. A discussion of typical properties of ABS resins are described on pages 1-64, 1-66, and 1-68 of Charles A. Harper's "Handbook of Plastics and Elastomers" which is published by McGraw-Hill Book Company in 1975. These pages are hereby incorporated by reference. ABS resins are terpolymers which are, in general, derived from acrylonitrile, styrene, and butadiene. Most are true graft polymers in which acrylonitrile and styrene are grafted onto a polybutadiene or rubber phase which may further be dispersed in a rigid styrene-acrylontrile (SAN) matrix. Other ABS resins are mechanical polyblends of elastomeric and rigid copolymer, e.g. butadiene-acrylonitrile rubber and SAN. (See. G. C. Hawkins, "Condensed Chemical Dictionary", 10th Edition, p. 3, 1981 as well as U.S. Pat. Nos. 4,107,232; 4,206,290; 4,487,886; 4,567,218; and 4,579,906 all of which are incorporated herein by reference. Hawkins, supra, defines ABS resin as: "Any group of touch, rigid thermoplastics deriving their name from the three letters of the monomers which produce them; Acrylonitrile-Butadiene-Styrene. Most contemporary ABS resins are true graft polymers consisting of an elastomeric polybutadiene or rubber phase, grafted with styrene and acrylonitrile monomers for compatibility, dispersed in a rigid styrene-acrylonitrile (SAN) matrix. Mechanical polyblends of elastomeric and rigid copolymers, e.g., butadiene-acrylonitrile rubber and SAN, historically the first ABS resins, are also marketed.
Varying the composition of the polymer by changing the ratios of the three monomers and use of other comonomers and additives results in ABS resins with a wide range of properties.
The general chemical structure of ABS is ##STR1## wherein x, y, and z may independently vary from about 10 to about 1,500. (See U.S. Pat. No. 4,567,218, the teachings of which are incorporated herein by reference.) It should be understood that analogs of each of the monomeric components above may be substituted in whole or in part, and is within the definition of ABS resin. For example, .alpha.-methylstyrene may be substituted for styrene and methacrylonitrile for acrylonitrile. Descriptions of the compositions of various ABS resins and how they are prepared may be found in U.S. Pat. Nos. 2,505,349; 2,550,139; 2,698,313; 2,713,566; 2,820,773; 2,908,661; 4,107,232; 4,173,561; 4,200,702; 4,206,290; 4,289,687; 4,355,126; 4,379,440; 4,456,721; 4,487,886; and 4,581,403, the teachings of which are incorporated herein by reference.
The ABS resins are useful in many commercial applications such as automotive, business machines, telephone, etc., where high impact strength is required as well as in the production of molded articles.
The use of brominated and/or chlorinated compounds by themselves or in combination with other materials such as organic phosphates, boron compounds, etc. as flame retardants for ABS resin compositions are well known in the art and are exemplified by U.S. Pat. Nos. 4,051,101; 4,051,105; 4,096,206; 4,107,122; 4,107,232; 4,173,561; 4,200,702; 4,289,687; 4,579,906; 4,355,126; 4,378,440; 4,567,218; 4,581,403; 4,581,409; and 4,600,747. The aforesaid patents are incorporated herein by reference.
Tetrahalophthalate esters have been used as flameproofing materials. For example, U.S. Pat. No. 4,098,704 describes the use of these materials as textile finishing agents. U.S. Pat. Nos. 4,298,517 and 4,397,977 disclose these compounds as flame retardants for halogenated resins. However, no teachings have been found which show these compounds as flame retardants or processing aids for ABS resins.